表达异步/等待返回未定义

Question

I am working on an express app and trying to use asyn/await in my route. Right now it doesnt seem to me waiting for the findOneUser call to return and is skipping to the next line:

app.post ('/api/authenticate', async(req, res) => {
  console.log('GET TO AUTHENTICAE')
  const { email, password } = req.body;
  const user_db = await users.findOneUser( email );
  console.log("user_db", user_db)
  return user_db
});

 const findOneUser = (email) => {
    console.log("email", email)
     pool.query('SELECT * FROM users where email = $1', [email], (error, results) => {
      if (error) {
        throw error
      }
      console.log("RESULT", results.rows)
       results.rows
    })
  }

Here are my logs in the terminal, you can see the user_db_log is showing up before the RESULT log but my understanding of async/await is that the user_db code should have waited for the user.findOneUser method to run:

GET TO AUTHENTICAE

email example@outlook.com

user_db undefined

RESULT 

[
  {
    id: 11,
    first_name: 'Test',
    last_name: 'User',
    email: 'testuser@test.com'
  }
]

Answer 1

try this way using Promise and async, await

 app.post ('/api/authenticate', async(req, res) => {
      console.log('GET TO AUTHENTICATE')
      const { email, password } = req.body;
      const user_db = await users.findOneUser(email);
      console.log("user_db", user_db)
      return user_db;
    });


 const findOneUser = async (email) => {
        var myPromise = () => {
            return new Promise((resolve, reject) => {
                pool.query('SELECT * FROM users where email = $1', [email], (error, results)=> {
                    error ? reject(error) : resolve(results);
                });
            });
        }
        var result = await (myPromise());
        return result;
  }

Answer 2

Await waits until the promise resolves.

But your findOneUser function is not returning promise and hence await immediately execute then returns.

So to make it work either add async{adding async to a function returns response wrapped in a promise} to your findOneUser function or create a promise inside the same function then return the response wrapped in promise.